1. Field of the Invention
The present invention relates to a method for producing a brush, especially a tooth brush, comprising the steps of unwinding a strand of a single filament or of a filament bundle from a spool and moving it past a cutting means in which a predetermined length piece of the strand is cut off, and connecting said length piece to a bristle carrier. Such a method is known e.g. from U.S. Pat. No. 2,643,158.
2. Description of the Related Art
In the case of the known method, a plurality of strands of filament bundles are unwound from spools simultaneously and supplied to a so-called perforated field plate which is installed in an injection mould later on, so as to complete the same. The unwinding of each individual strand from the spool and the introduction of the strand into the perforated field plate are carried out by mechanically clamping each individual strand. A feed means is provided with a stationary clamping device and with a movable clamping device for each strand. The movable clamping device is moved towards the stationary clamping device. During this movement, the stationary clamping device is effective, i.e. the strand is held in position. Subsequently, the stationary clamping device is released and the movable clamping device is activated. The movable clamping device is moved away from the stationary clamping device in the direction of transport. In the course of this movement, additional strand material is unwound from the spool and the front free end of the strand is also introduced in the perforated field plate.
A similar means which also touches the strands supplied is known e.g. from U.S. Pat. No. 3,408,112. German-Offenlegungsschrift 25 52 213 and e.g. German-Offenlegungsschrift 28 49 510 disclose that the strands are guided and advanced between two driven feed rolls. In comparison with the first-mentioned solution, this solution entails the problem of slip between the strand and the feed rolls. The desired feed of the strand is not reliably achieved.
In the case of the two above-mentioned methods, the strand is seized or rather clamped behind its front free end and advanced by means of said clamping, so that special care is required when threading the strand, so as to avoid kinking of the individual filament or of individual filaments of a bundle of filaments. Such kinking of the filaments will impair the process. Especially in the case of the nowadays normally used high processing speeds, such kinking will cause high reject rates and, in some cases, the whole production process will be brought to a standstill.
In addition, the conveying means which are known from the prior art and which serve to unwind and advance the strand for connecting the same to a bristle carrier later on, have a structurally conditioned inertia. This limits the maximum possible processing speed. The mechanical parts are, moreover, complicated as far as their structural design is concerned and they necessitate a great deal of maintenance work.